Pricing boards are commonly used in restaurants, cafeterias, liquor stores, and the like to indicate prices of various products. As the prices may change frequently, it is necessary to reflect the price changes on the pricing board.
One common form of pricing board utilizes fonts, which are individual letters or numerals, having tabs or projections which can be inserted within grooves in the pricing board. With this type of pricing board, a large inventory of fonts is required and frequently the fonts are misplaced or damaged. In addition, a substantial amounts of time is required to individually remove each font from the board, replace the font in the storage container, select the new font and insert it onto the pricing board.
More recently, pricing boards have been constructed with a series of windows or openings and a rotatable drum bearing numerals or indicia is mounted for rotation behind each window. By manually inserting the finger through the window, the drum can be rotated to expose the desired indicia in the window. While the use of the rotating drum simplifies the changing of prices, the drums are relatively expensive, due to the fact that they are normally formed of injection molded plastic. Furthermore, it is costly to apply the indicia to the curved outer periphery of each drum.
As a further disadvantage, the rotary drum-type of indicia display cannot satsifactorily be illuminated from the rear, and as the indicia is located on a curved surface, it may, depending on the radius of curvature, appear somewhat distorted to the viewer. In addition, each rotary drum is required to have some type of friction brake mechanism to hold the drum in position and prevent free rotation. As a further drawback, a substantial depth of casing or enclosure is required for housing the drums, and thus the rotary drum type of display is not acceptable in certain installations which require a minimum depth.
More recently, flexible, stressed polyester tape has been used in pricing boards and similar types of displays. In this construction, the tape is stressed so that it is pre-coiled and the ends of the tape are maintained in the coiled condition without the need of a spindle or axle. The tape bearing the indicia is fed through a guideway and exposed through a window in the casing. As in the case of the drum type, the prices are changed by inserting the finger through the window and manually moving the tape to expose the desired indicia.
The pre-stressed tape system is relatively expensive for it requires an individual tape to be located behind each window in the pricing board. Furthermore, as the tape is not maintained on a spindle, but is freely coiled, it has a tendency to kink as it is pushed by the finger, with the result that permanent kinks or deformities can destroy the reliability of the unit.
With the pre-stressed tape it is not practical to form a laminated sandwich tape structure. Thus, the printed indicia is exposed on one surface of the tape, with the result that the printing is invariably scratched or marred with use, as it is pushed back and forth by the user.
As the pre-stressed tape is not in an endless form, at times, it is necessary that the entire tape be reversed to obtain the desired numeral, or other indicia in the viewing window. To prevent the tape from being pushed completely out of the guideways, it has been necessary to put a warning such as "stop" at the ends of the tape, and this increases the length of the tape that is required and the overall cost of the unit.
As a further disadvantage, the pre-stressed tape system tends to bind when pushed through the guideway with the result that it is often necessary to apply a powdered lubricant in order to facilitate movement of the tape.
As the coiled ends of the tape project rearwardly a substantial distance beyond the portion of the tape which is being viewed through the window, the coiled ends provide an obstruction to direct illumination of the exposed indicia.
In addition to the mechanical forms previously described, electronic pricing boards have also been used. However, electronic systems are very expensive and thus do not normally lend themselves to use in restaurants, liquor stores, and the like.